Trash won't empty in 10.7.4

Weird issue folks. Can't get the trash to empty the normal way, I have to use OnyX to do it. Checked system with disk utility etc and all checks out ok. Files that are trashed are not locked either. Has anybody else experienced this since updating to Lion? It just recently started, as when I first updated to Lion everything was working normally. No clue as to what could have caused this minor problem.